This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Conveyor belts have at least one carcass, which transmits tensile force and is made of textile and/or steel-cord inserts, generally surrounded by at least one adhesive rubber mixture. Surrounding the carcasses on all sides there are wear-resistant outer rubber sheets and a rubber edge-protection system. There can also, if required, be various arrangements present to prevent any kind of penetration.
Conveyor belts where the carcass consists essentially of steel cords are known as steel-cord conveyor belts. Steel-cord conveyor belts can provide excellent transport performance even under very adverse conditions. Their robust structure guarantees both high breaking strength when very high levels of conveying performance are required and also good resistance to harsh treatment. They are generally particularly abrasion-resistant, rot-resistant, and corrosion-resistant, and resistant to chemicals and to heat, thus ensuring a long lifetime with little need for maintenance.
The arrangement of the steel cords in the steel-cord conveyor belt mostly takes the form of layer in a plane between the outer sheets. For reasons related to adhesion and to prevention of corrosion, the steel cords are often galvanized cords, mostly with diameter from 2.8 to 16.0 mm, and can be composed of about 40 up to 250 individual wires.
In order to improve adhesion, adhesive mixtures, also known as adhesive rubber mixtures, are often also used, intended not only to optimize adhesion but also to flow into the steel cords during the vulcanization process in order to allow better sealing. Full penetration through the entire cord, also known as full rubberization, is essential for the lifetime of the steel cord and therefore also for the entire conveyor belt. If full rubberization does not take place, cavities in the cord structure remain available, and it is thus possible that, by way of example, liquids such as water, oils, etc. can migrate within the cord, and progressive oxidation processes, in particular corrosion, can occur, with increased aging and premature failure of the entire conveyor belt. Full penetration of the entire cord structure becomes more difficult as the diameter of the cord increases. In “closed” cord structures, which are also known as parallel-lay or lang-lay structures it is almost impossible to achieve full penetration even with relatively small diameters.